Heat regulating apparatus



P 1935- L. CUNNINGHAM 2,013,266

HEAT REGULAT ING APPARATUS Filed Sept. 4, 1951 I INVENTOR LEWIS L.. UNNINGHAM y M MM ATTQRNEY5 Patented Sept. 3, a 1935 PATENT OFFICE HEAT momma APPARATUS Lewis L. Cunningham, Minneapolis, Minn., as-

signor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application September 4, 1931, Serial No. 561,228

8 Claims.

This invention relates to improvements in heat regulating apparatus and is broadly directed to precision means for controlling a burner apparatus by the cooling movement of a thermally operableswitch control element which has been pre- It is particularly desirable to provide an elec trically controllable timing device in which the timing period will not be varied as the result of any fluctuation in the power supply, more particularly in line voltage.

Objects of the present invention are, therefore,

to provide means for operating a burner apparatus to produce and continue production of flame; to provide a device which is responsive to flame and which will continue burner apparatus operation'when flame is present; to provide an ignition timing device, the operation of which can be controlled by a thermally controlled switch, so that the timing device is conditioned for operation upon a call for heat; to provide means whereby the circuit to the burner motor cannot be closed until after the thermal portion of the timing device has been heated to a predetermined temperature; to provide means to close the burner motor circuit as soon as the timing device has been heated to the predetermined temperature and simultaneously discontinue heating of the timer, to the end that the cooling movement only of said thermal element from' a predetermined heated condition may be utilized to open the motor circuit at the end of a predetermined time period, if flame is not produced, the time required for the maximum cooling to take place being the measure of the .trial ignition period; and to provide an arrangement of the circuits whereby the heating coil of the thermal device is rendered inactive during the full timing by cooling period.

Features of the invention include; with the broader aspects, all details of construction as well as the combination and subcombination of the parts, along with means for interrupting heat supply to a thermally operable switch control element, after this element has been heated to a interval between the energization of cofl I and the predetermined degree, to allow the thermal element to cool, and means for preventing reenergization of the thermally operable switch in case ignition is not successful or in case of flame failure during normal operation of the apparatus.

Objects, features and advantages of the invention will be set forth in the description of the drawing forming a part of this application, and said drawing comprises a single diagrammatic view illustrating one embodiment of the invention and showing the positions of the parts when the device is inactive.

The burner motor is indicated at 3 and fuel will be fed when the motor operates. An expanding flame pilot device 66 represents a convenient form 1 of ignition means. The device 66 represents an electromagnetic gas valve of the type that provides a. constant minimum flow of gas to a burner, and when energized, increases the flow of gas, Other forms of ignition may be used. Electrical means for controlling burner apparatus operation includes a first relay or equivalent device designated No. 1, of which numeral I indicates the coil, the circuit to which is partly controlled by room thermostat RBW. This relay controls an armature 9 which in turn controls holding contact (through room thermostat Rr-BW) II-I5 for coil I during operation of the burner motor; contact I2-l6 which is one of the contacts controlling theshunt circuit for coil I during the heating period of the thermal electric trial ignition timer, and opening on energization of coil I; and contact I3-I'I controlling motor and ignition means energization, closing on energization of coil I.

Thermal electric means is provided and is adapted for timing a trial ignition period (when cooling), and includes in this instance a warp switch having a heating coil 32, thermal element 33 and electrically connected contact arms 3|, which respectively-engage with contacts 31-38. the contacts being, in this instance, overlapping so that each is made before the other is broken. Normally, contact 3'I34 is closed as shown in the drawing. The breaking ofthis contact corresponds to the predetermined heated condition of element 33 at which time the shunt circuit to coil I is broken, resulting in energization of coil I and closing of the motor contact I3I|. The

breaking of contact 35-38 is the measure of a trial ignition period which is controlled by the cooling motion of the thermal element 33.- Con-v tact 35-48 is made, however, before contact 34-31 is broken and the making 01' contacts -38 and I 'l|5 establishes a temporary holding circuit for the coil l while the element 33 is cooling or performing its trial ignition timing function. A compensating bimetallic blade 33a is securedto thermal element 33 by means of heat insulating block 33b to compensate for changes in ambient temperature in the usual well known manner.

Means, electrical and mechanical, interconnect the burner apparatus and ignition means, burner apparatus control means, and thermal electric means, in a manner to cause the element 33 or its equivalent to be moved in one direction until it has been heated to a predetermined degree, and after such motion to initiate a trial ignition operation ofthe burner apparatus and simultaneously prevent further heating and motion in the same direction, then maintain the burner and ignition apparatus in trial ignition condition while said element moves in an opposite direction, and then stop burner and ignition operation if ignition is not successful during such reverse motion. The feature is that the arrangement must be such that motion in that direction which corresponds to the trial ignition cannot be interfered with-by any part of the apparatus.

A second relay designated No. 2 is'also provided, the coil of which is shown at 2, and includes in its circuit a thermal switch member 69 adaptedergize coil 2 of No. 2 and move armature 25 to the left. This armature controls three contacts, namely, contacts 26-29, 21-30, and 28i-3i. The contact 2629 partly controls a permanent holding circuit for relay No. 1 during normal operation of the apparatus after flame is produced. Contact 2l--3ll partly controls the circuit to the heating coil 32 and is opened on production of flame as the result of energization of coil 2. Contact'28-3l upon opening as a result of energization of coil 2 deenergizes the ignition means 66, even tho contact l3-Il is closed. n

The armatures 9 and 25 respectively of relays Nos. 1 and 2 cooperate to control a starting contact .l0lfi. Element 10 is carrled'by a rigid member Illa whereas element It is carried by a springarm Ida normally biased to cause engagement of elements It! and M. Armature 9 is pivoted to member Illa as shown at 911 and is prospring arm Ma and when IB-M is opened as a result of energization of coil I, the lower end of latch 46 is positioned above spring arm lea (shown by dotted lines in the drawing) by means of spring d9 to hold element It out of engagement with element in after armature 9 returns to its normal position Armature 25 of relay No. 2 is provided with a pin which engages latch 36 upon energization of coil 2 and moves the same to its full line position wherein we is free to cause engagement of elements It and i0 when relay No. 1 is deenergized.

It will be apparent then, that starting contact I fi-J is normally closed during non-operating periods of the burner apparatus. Upon a call for heat and subsequent energization of relay No. 1, starting 'con'tact ill-l6 is opened and latched in open position by latch as. The aement is such that holding contact I |-l5 of relay No. 1 is closed before contact Ill-i4 is opened. If flame is not produced relay No. 2 is not energized and relay No. l is deenergized at the end of the trial ignition period. Starting contact Ill-M istherefore latched in open position and must be reclosed manually before another trial operation of the burner apparatus can be initiated. If flame is produced, relay No. 2 is energized andv armature 25 thereof moves latch 46 to inoperative position. on a call for cold, relay No. 1 will first be deener gized allowing starting contact Ill-l4 to close and relay No. 2 will subsequently be deenergized when flame responsive contact 68-,69 opens whereupon latch 46 will assume its full line position.

The control apparatus includes a step-down Operation Assume a call for heat at the room thermostat and closure of contacts B, W. This closure will result (if the electrical apparatus. is in proper condition) in providing heat for the heating element 32, by the following circuit: Secondary 8, wire 80, W, R, B, wire 82, contact 3ll2'l, wire 88, element 32, wire 8'7, contact l0--M, wire 95, 86, 5 3, 31, 93', contact l2--it, 9i, and wire 89 back to secondary 8. It will be noted that coil l isshunted by 86, 56, 37, 93, I2l6, and SL Heating of element 33 begins and when it has received enough heat, arm 35 will engage contact 33. Engagement of 35 with 38 partially completes a holding circuit later to be described. When the predetermined amount of heat has been transmitted to element 33, arm 3d will be moved from engagement with 31. It is to be noted that separation of 34 and 31 is the result of a predetermined amount of heat having been transmitted to element 33, regardless of the length of time that current has been flowing through heating element 32 and regardless of fluctuations in voltage.

Separation of 35 from 31 breaks the shunt circuit for coil 5 and this coil now becomes energized attracting armature 9. Movement of armature 9 opens starting contacts lU-lfi to deenergize heater 32. Opening of l2-l6 provides another gap in the'shunt circuit for coil 1 so that the coil I will remain energized when 36 engages 31 during cooling movement of element 3,3. Closure of H--|5 provides the following temporary holding circuit for coil I, the energizing circuit having been broken at lD-ll: secondary ,8, 80, W, R, 8|, ll-I 5, 85, 38, 35, 84, coil I, and 89 back to 8. Closure of l t-ll energizes motor 3 as follows: line 6, b, l3ll, 61, motor 3, 60a and line 5. Closure of l3-l'l also energizes ignition means 66 as follows: line 6, 60b, l3ll, 6|,10, 28-3I, ll, 55,. and to line 5. At this time, starting contact Ill-44 is latched in open position by latch 35.

Element 33 is now cooling, motor and ignition are energized and a trial ignition period is progressing. In the cooling motion of element 33, arm 3Q first engages 37. This closure has no effact since the shunt circuit for coil 1 has been opened at l2l,5. Assuming that combustion does not take place, the cooling movement of element 33 will finally cause arm 35 to leave 38 whereupon the temporary holding circuit for coil 8 is openedl Starting contact Iii-N is already latched open and the apparatus is shut down and cannot be restarted until Ill-l4 is closed manually. The time required for element 33 to move from its hot position to the position in which 35 leaves 38 will be extremely accurate,

. is always provided with exactly the same amount of heat before a trial ignition period bycooling is instituted.

The element 33 is compensated for changes in ambient temperature by the compensating element 33a. The same amount of heat is always required to close 35--38 and to open 3fl31. If the amount of line voltage should be reduced, less heat will be given ofi-by heater 32 per unit of time, but the element 35 will not be moved to its extreme position until a predetermined amount of heat hasbeen transferred to it. If the line voltage should be lowered, a longer period of time would be required to supply this heat than would be the case if the voltage were at the proper value. The element 33 having been heated to a predetermined degree irrespective of voltage fluctuations, it follows that it will always require the same amount of time to cool, after the heater coil 32 is de-energized.

Going back to the point where relay No. 1 has just been energized and assuming that combustion takes place resulting in closure of contact 68-69 before the arm 35 leaves 38, the following energizing circuit for coil 2 will be established: line 5, 50, coil 2, 67, 6869 back to line 6. Armature 25 is attracted opening contact 28-3| to deenergize the ignition means 66. Contact 21-30 is opened to prevent heating of element 32 when relay No. 1 is deenergized on a call for cold and before contact 6869 opens. Contact 26--2 is closedto establish the following permanent holding circuit for coil I: secondary 8, 80, W, R, 8|, ll-i5, 99, 26-29, 83, 84, coil l, 89 back to 8. Movement of armature 25 also moves latch 46 to its-full line position. When the room thermostat becomes satisfied, the permanent holding circuit for coil i is broken at W and armature 9 returns to its full line position allowing starting contact III-l4 to close and the motor 3 is deenergized. An immediate reclosure of W, R, B, will have no effect since the starting circuit is open at21-30. energization of motor 3, combustion responsive contact 68-459 will'open, deenergizing coil 2 and the apparatus is now ready for a new start.

If the flame should fail while the burner is operating, contact 68-69 will open deenergizing coil 2. Armature 25 will fall out latching starting contact |0l4 in open position and breaking the permanent holding circuit for coil i at 2&- 29. The apparatus will therefore be shut down and cannot be started again until Ill-44 is manually closed.

If the power should fail, both relays will be deenerglzed at the same time. The relays and latchingmechanism are adjusted however so that relay No. 1 falls out enough before relay No. 2 to allow starting contact Ill-A i to close. The apparatus will therefore recycle on resumptidn of power. Relay adjustment whereby two relays may be made to drop out at slightly spaced intervals on interruption of power to both is old in the art.

From the foregoing description, it will be seen that this invention provides an accuracy in timing by a thermal element which has been impossible to obtain by prior devices. This accuracy is obtained by heating the thermal timer to a predetermined degree measured by movement of the thermal element, and timing by the period re- Several seconds after the dequired for the element to cool from this predetermined heat content again measured in termsof movement of the thermal element.

Accurate timing is of special importance in th field of automatically ignited gas fired devices and the term moto or burner motor as used in the claims includes any electrically operated device for controlling th flow of fuel to a burner.

I claim as my invention:

1. A control system comprising, in combination, an electromagnetic coil, a switch moved to open position upon energization of said coil, latch means for latching said switch in open position, a thermal electric timer including an electric heating element, starting and holding timer operated switches, a main control, an energizing circuit for said heating element including said first named switch, the timer starting switch and the main control, a starting circuit for said electromagnetic coil controlled by said main switch and timer starting switch, a holding switch operated by said electromagnetic coil, a holding circuit for the electromagnetic coil controlled by said main control,

coil operated holding switch and timer operated holding switch, a circuit controlled by said electromagnetic coil, a burner motor in said circuit, and means responsive to the presence of combustion for operating said latch means to unlatch said first named switch for return to closed position upon de-energizatio'n of said electro-magnetic coil and for maintaining said electro-magnetic coil energized independently of said timer holding switch.

2. A control apparatus comprising a burner motor, an igniter, a thermal timer including a heater, a main switch, first and second relays, a timer circuit contact controlled by the first relay to close and open respectively when the first relay is de-energized and energized, means for energizing the second relay on production of combustion, a main-switch-controlled energizing circuit for the heater operative only when both relays are de-energized, and at or near the end of a cooling cycle of the timer, amain-switch-controlled energizing circuit for the first relay closed during a heating cycle and opened during a cool- ;ing cycle ofthe timer, a main-switch-controlleo temporary holding circuit for the first relay closed during a heating cycle and opened at the end of a cooling cycle, ,a main-switch-controlled permanent holding circuit for the first relay operative only while both relays are energized, means by which energization of the first relay energizes the motor and igniter, and means by which energization of the second relay de-energizes the igniter.

3. A control apparatus comprising a burner motor; an igniter; a timer and heater therefor, said timer controlling two contacts to close the first contact and then open the second while the heater is heating and to close the second and open the first when the heater is cooling; a main switch;

first and second relays; a contact controlled by both relays to be opened on energization of the first relay to be closed when both relays simultaneously open, and to be locked in open position if the first relay is deenergized while the second is de-energized; combustion responsive means controlling the second relay to energize it when combustion is produced; a circuit for the first relay including. a shunt circuit which must be opened to obtain energization of the first relay and which passes through the main switch, a first contact of the second relay, said heater, the two-relay-controlled contact, the second contact of sa d timer and a first contact at said first relay; a temporary hold- 4 5 ing circuit for the first relay passing through said main switch, a second contact of thefirst relay and the first contact of the timer switch; a-perrnanent holding circuit for the first relay. which is independent of the timercontacts, and dependent on a'second switch of the second relay when the latter is energized while-thefirst relay is energized; and means by which energization of the first relay-while the second relay is de-energized, energizes the motor and igniter; and means operative on energization of the second relay while the first is energized, to de-energi'ze the igniter.

4. A control system including first and second relays; a first contact and means by which it is controlled by both relays to be opened on energization of the first relay, to be closed when the first relay is deenergized with the second relay energized, and be locked in open position if the first relay is deenergized while the second relay is deenergized; a thermal electric timing switch and an electric heater therefor; a circuit for the heater having therein a main switch, a contact closed by the second relay when deenergized, said first contact, said timing switch, and a contact of the first relay which is closed when the first relay is deenergized; a starting circuit for the actuating means for the firstrelay including said main switch, said contact of the second relay, said heater, and said first contact whereby said starting circuit is operatively energized upon actuation of the timing switch after a predetermined heating of the thermal element thereof by said electric heater; a holding circuit for said first relay maintained through said timing switch until a predetermined amount of cooling has taken place; fuel feeding means controlled by said first relay to feed fuel when said first relay is energized; a fiame responsive switch in control of the second relay ,to energize-the same when flame is present; and a maintaining circuit for the first relay which is independent of said timing switch controlled by the second relay when energized whereby to maintain fuel feed if combustion is established.

5. A control system including first and second relays; a first contact and means by which it is controlled by both relays to be opened upon energization of the first relay, to be closed when both relays are simultaneously deenergized, and to be locked in open position if the first relay is de-' energized while the second relay is' deenergized; a thermal electric timing switch andan electric heater therefor; a circuit for the electric heater in shunt around the actuating means of the first relay and having therein a main switch, a contact closed by the second relay when the same is deenergized, said first contact, said timing switch,

and a' contact of the first relay which is closed when the first relay is deenergized; 'means by which the actuating means of the first relay is through the timing switch to maintain energizationfof the first relay for a predetermined cooling of the thermal timing means, a burner motor and circuit therefor controlled by the first relay to close when the first relay is energized; ignition means and a circuit therefor controlled by the second relay to open when the second relay is energized, a switch adapted to close on production of flame; a circuit by which said switch controls the second relay to energize it on switch closure; and a second holding circuit for the first relay independent of said timing switch and controlled by both relays whereby upon the establishment of combustion during the said cooling period, motor energization is maintained.

. 6. A control system including first and second relays; a first contact .and means by which it is controlled by both relays to be opened on enerr gization of the first relay, to be,closed if the second relay is not deenergized prior to the first relay, and to be locked in open position if the first relay is deenergized while the second relay is deenergized; a thermal electric timing switch and heater therefor; a circuit for the heater which shunts the actuator of said first relay and having therein a main switch, va contact closed by the second. relay when the same is deenergized, said first contact, said timing switch, and a contact of the first relay which is closed when the first relay is deenergized; a circuitfor the actuating means of the first relay which is operatively energized upon opening of said timing switch after the same has been heated to a predetermined degree and including therein said main switch, said contact of the second relay, and said first contact; a burner motor and circuit therefor controlled by the first relay and completed when the first relay is energized; ignition means and a circuit therefor controlled by the second relay, which circuit is opened when the second relay is energized; a switch adapted to close on production of fiame; a circuit by which said switch controls the second relay to energize it on switch closure; and a circuit controlled by 'said second relay when energized for maintaining energization of the first relay.

7. A control system including a first relay; a

second relay; a room thermostat; atiming switching means and a heater for controlling the timing switching means motion; a'circuit for the heater in shunt with the actuator of said first relay and having therein said thermostat, a contact controlled by said second relay, said heater, a first contact of said first relay; said timing switching means, and a second contact of the first relay; a circuit for the actuating means of the first relay operatively energized upon opening of said timing switching means upon being heated to a predetermined degree andincluding therein said thermostat, said contact of said second relay, the heater, and said first contact of the first relay;

latching means associated with said first contact and controlled by both relays to lock said first switch in open position when said first relay is deenergized while the second relay is deenergized and by which such locking is prevented when said first relay is not deenergized prior to deenergization of said second' relay; a fuel feeding apparatus including a burner motor; a circuit.

therefor controlled bysaid first relay to close when the first relay is energized; ignition means;

a circuit therefor controlled by the second relay to open when the second relay is energized; a

circuit for controlling the second relay and having therein a switch adapted to close on production of flame; and a maintaining circuit for the first relay controlled by said thermostat and a switch operated by said second relay when energized.

8. A control system including a first relay; a second relay; a room thermostat; a timing switching means including hot and cold contacts and a heater for controlling the timing switching means motion; a circuit for the heater in shunt with the actuator of said first relayand having therein said thermostat, a contact controlled by said second relay, said heater, a first contact of said first relay, said timing switch means, and a second contact of the first relay; a circuit for the first relay rendered operative upon opening of said timing switching means cold contact after the timing switching means has been heated to a predetermined degree and including therein said thermostat, said contact of the second relay, the heater, and said first contact; a holding circuit for the first relay having therein said thermostat, a holding contact of said-first relay, and said timing-switching means hot contact; latching means for said first contact by which said first contact is locked in open position when the first relay is deenergized while the second relay is deenergized and by which such locking is prevented when said relays are simultaneously deenergized; the holding contact of the first relay being adapted to close before the opening of said first contact on energization of the'first relay; a burner motor and circuit therefor controlled by said first relay to be completed when the first relay is energized; ignition means; a switch that closes on production of fiame; an energizing circu'it for said second relay controlled by'said lastnamed switch; and a second holding circuit for said first relay controlled by a second switch operated by the second relay when closed by said thermostat. V

LEWIS L. CUNNINGHAM. 

